Bubbl.us - http://www.bubbl.us - Online mind-mapping tool. Collaborate with others and/or embed online.
Mind42 - http://www.mind42.com - Collaborative mind mapping in your browser (sort of like Inspiration)
ShareTabs - http://sharetabs.com - Creates a single URL of your browser tabs to share with others.
sketchfu - http://sketchfu.com/home - Online whiteboard. Draw images for play-back. Create a class account for students to log in and share drawings of story maps, processes, solving problems, and drawings.
Storybird - http://storybird.com - Digital story telling sight. Images provided, text added by user.
Wallwisher - http://www.wallwisher.com - Online post its. Great for student share-out or parking lot questions. Tom Barrett has a collection of ways to use Wallwisher in the classroom HERE.